1. Field of the Invention
This invention relates to a portable hydraulic press for making building blocks from earth, and more particularly to a machine which makes such blocks rapidly and inexpensively.
2. Description of the Prior Art
The use of earthen blocks as a building material to form structures has been known for thousands of years. Recently, there has been renewed interest in building structures of earthen blocks because of the ready availability of the earth and because of the unique properties of earth which makes it an ideal building material. Earth is available in unlimited supply at no expense, and it is available at the site of construction. In addition, earth is non-toxic, non-allergenic, fireproof, and soundproof. The high insulation properties also enhance its desirability as a building material.
The earth available at the building site has traditionally been fashioned into building blocks using one of two different methods. The first method is to form the earth into a permanent block using relatively low pressures, and then to dry the block in the sun to set the block in shape. The earth is often mixed with straw. This method is commonly known as adobe. The adobe construction requires molding and prebaking in the sun which requires considerable time and favorable weather.
The second method requires compression of the earth in a suitable machine having a high pressure ram. In order to form the earth into building blocks, it is necessary to provide a machine which is portable and which is capable of providing high pressures to form the earth into a solid block. Pressures of up to 3,000 psi (210 kg./sq. cm.) may have to be produced in order to form a solid earth block from the variety of types of earth available around the world. However, it is difficult to achieve such a high pressure in a portable machine using a small lightweight hydraulic cylinder.
Machines capable of producing such high pressures are often very slow because the hydraulic ram capable of producing high pressures usually operates at a very slow speed. Therefore, the production rates of such high pressure machines are usually fairly low. Such a machine should eliminate wasted motion as much as possible, and it should be relatively fast so that the earth blocks can be produced rapidly.
Although earth is available in unlimited supply free of charge, the cost of providing earth blocks may be drastically increased due to the cost of forming the earth into blocks. Therefore, a machine for forming building blocks of earth should be highly efficient to reduce the cost of forming the blocks as much as possible and take advantage of the low cost quality of earth building blocks. Such a machine should be as efficient as possible in order to keep fuel prices to a minimum so that low cost production can be achieved. When using the hydraulics, the hydraulic supply should be kept as close as possible to the cylinder so that friction losses are reduced as much as possible. The hydraulic line should also be free of sharp curves in order to reduce losses in the hydraulic lines.
While such a machine should be operating rapidly with very high pressures, it is necessary for such a machine to be relatively simple to operate. The machine should operate automatically and be capable of operation by semi-skilled labor, so that the machine can operate with little supervision and with a minimum number of operators. The requirement of a skilled operator or of multiple operators increases the costs of operating the machine and thereby defeats the low cost advantage of using earth as a building material.